Not Turn-On

The only other thing I can think of is the type of battery.

If you are currently using the NiMH AA rechargeable batteries, I would suggest you try standard Alkaline AA batteries. They have a bit more voltage than the NiMH and it might make a difference in this case.

If that does not work, you should phone Panasonic Service and see if they have any suggestions.
I am sure they have encountered this problem before.